H1B to H4 Visa - Dropbox eligibility

Hi

I am trying to find if I am eligible for dropbox facility to get H4 visa stamped in India.

I am currently on H1B visa stamped in India in December 2017, and valid till April 2020. My H4 visa was also stamped in India in July 2016 and valid till June 30, 2018. If I apply for H4 visa in July 2018 in India, will I be eligible for dropbox. My husband H1B extension is from the same petitioner as it was in July 2016. He is eligible for dropbox. Please let me know if you need more information.